Baier Felix, Reinhard Katja, Nuttin Bram, Sans-Dublanc Arnau, Liu Chen, Tong Victoria, Murmann Julie S, Wierda Keimpe, Farrow Karl, Hoekstra Hopi E
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
Nature. 2025 Jul 23. doi: 10.1038/s41586-025-09241-2.
Evading imminent threat from predators is critical for animal survival. Effective defensive strategies can vary, even between closely related species. However, the neural basis of such species-specific behaviours remains poorly understood. Here we find that two sister species of deer mice (genus Peromyscus) show different responses to the same looming stimulus: Peromyscus maniculatus, which occupies densely vegetated habitats, predominantly escapes, whereas the open field specialist, Peromyscus polionotus, briefly freezes. This difference arises from species-specific escape thresholds, is largely context-independent, and can be triggered by both visual and auditory threat stimuli. Using immunohistochemistry and electrophysiological recordings, we find that although visual threat activates the superior colliculus in both species, the role of the dorsal periaqueductal grey (dPAG) in driving behaviour differs. Whereas dPAG activity scales with running speed in P. maniculatus, neural activity in the dPAG of P. polionotus correlates poorly with movement, including during visually triggered escape. Moreover, optogenetic activation of dPAG neurons elicits acceleration in P. maniculatus but not in P. polionotus, and their chemogenetic inhibition during a looming stimulus delays escape onset in P. maniculatus to match that of P. polionotus. Together, we trace species-specific escape thresholds to a central circuit node, downstream of peripheral sensory neurons, localizing an ecologically relevant behavioural difference to a specific region of the mammalian brain.
躲避来自捕食者的迫在眉睫的威胁对动物的生存至关重要。有效的防御策略可能各不相同，即使在亲缘关系密切的物种之间也是如此。然而，这种物种特异性行为的神经基础仍知之甚少。在这里，我们发现鹿鼠属（Peromyscus）的两个姐妹物种对相同的逼近刺激表现出不同的反应：占据茂密植被栖息地的北美鹿鼠（Peromyscus maniculatus）主要选择逃跑，而旷野专家佛罗里达白足鼠（Peromyscus polionotus）则会短暂静止不动。这种差异源于物种特异性的逃跑阈值，在很大程度上与环境无关，并且可以由视觉和听觉威胁刺激触发。通过免疫组织化学和电生理记录，我们发现尽管视觉威胁在两个物种中都会激活上丘，但中脑导水管周围灰质背侧（dPAG）在驱动行为方面的作用有所不同。在北美鹿鼠中，dPAG活动与奔跑速度成正比，而在佛罗里达白足鼠的dPAG中，神经活动与运动的相关性很差，包括在视觉触发的逃跑过程中。此外，对dPAG神经元的光遗传学激活在北美鹿鼠中会引发加速，但在佛罗里达白足鼠中则不会，并且在逼近刺激期间对它们进行化学遗传学抑制会延迟北美鹿鼠的逃跑起始时间，使其与佛罗里达白足鼠的逃跑起始时间相匹配。我们共同将物种特异性的逃跑阈值追溯到一个中央回路节点，该节点位于外周感觉神经元的下游，将一种与生态相关的行为差异定位到哺乳动物大脑的一个特定区域。
